# modprobe g_webcam
[ 13.884493] g_webcam gadget: uvc: uvc_function_bind()
[ 13.889574] g_webcam gadget: uvc: Unable to allocate streaming EP
[ 13.895850] g_webcam musb-hdrc.1.auto: failed to start g_webcam: -22
[ 13.905209] g_webcam gadget: uvc: uvc_function_bind()
[ 13.910284] g_webcam gadget: uvc: Unable to allocate streaming EP
[ 13.916566] g_webcam musb-hdrc.1.auto: failed to start g_webcam: -22
modprobe: can't load module g_webcam (kernel/drivers/usb/gadget/legacy/g_webcam.ko): Invalid argument发现 HI3518 也有一模一样的问题 http://bbs.ebaina.com/thread-39433-1-1.html
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https://devtalk.nvidia.com/default/topic/1036885/tx1-usb-uvc-gadget-troubles/
问题：
TX1的OTG端口是否支持等时模式？
是否有不同的方法来配置系统以解决此错误？
我可以提供其他日志/信息，以便更容易调试吗？
在设备模式下，OTG端口不支持等时模式。
看来有点悲剧了
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不知道这个补丁有没有用哦: https://gitlab-beta.engr.illinois.edu/ejclark2/linux/commit/f82a689faeb328ba7c194782f42cc438519d508e
musb_writew(hw_ep->regs, MUSB_RXCSR, val);
#ifdef CONFIG_USB_INVENTRA_DMA
if (usb_pipeisoc(pipe)) {
struct usb_iso_packet_descriptor *d;
d = urb->iso_frame_desc + qh->iso_idx;
d->actual_length = xfer_len;
/* even if there was an error, we did the dma
* for iso_frame_desc->length
*/
if (d->status != EILSEQ && d->status != -EOVERFLOW)
d->status = 0;
if (++qh->iso_idx >= urb->number_of_packets)
done = true;
else
done = false;
} else {
/* done if urb buffer is full or short packet is recd */
done = (urb->actual_length + xfer_len >=
urb->transfer_buffer_length
|| dma->actual_len < qh->maxpacket);
}
/* send IN token for next packet, without AUTOREQ */
if (!done) {
if (dma) {
struct dma_controller *c;
u16 rx_count;
int ret;
int ret, length;
dma_addr_t buf;
rx_count = musb_readw(epio, MUSB_RXCOUNT);
c = musb->dma_controller;
if (usb_pipeisoc(pipe)) {
int status = 0;
struct usb_iso_packet_descriptor *d;
d = urb->iso_frame_desc + qh->iso_idx;
if (iso_err) {
status = -EILSEQ;
urb->error_count++;
}
if (rx_count > d->length) {
if (status == 0) {
status = -EOVERFLOW;
urb->error_count++;
}
DBG(2, "** OVERFLOW %d into %d\n",\
rx_count, d->length);
length = d->length;
} else
length = rx_count;
d->status = status;
buf = urb->transfer_dma + d->offset;
} else {
length = rx_count;
buf = urb->transfer_dma +
urb->actual_length;
}
dma->desired_mode = 0;
#ifdef USE_MODE1
/* because of the issue below, mode 1 will
urb->actual_length)
> qh->maxpacket)
dma->desired_mode = 1;
if (rx_count < hw_ep->max_packet_sz_rx) {
length = rx_count;
dma->bDesiredMode = 0;
} else {
length = urb->transfer_buffer_length;
}
#endif
/* Disadvantage of using mode 1:
*/
ret = c->channel_program(
dma, qh->maxpacket,
dma->desired_mode,
urb->transfer_dma
+ urb->actual_length,
(dma->desired_mode == 0)
? rx_count
: urb->transfer_buffer_length);
dma->desired_mode, buf, length);
if (!ret) {
c->channel_release(dma);
}
}
if (dma && usb_pipeisoc(pipe)) {
struct usb_iso_packet_descriptor *d;
int iso_stat = status;
d = urb->iso_frame_desc + qh->iso_idx;
d->actual_length += xfer_len;
if (iso_err) {
iso_stat = -EILSEQ;
urb->error_count++;
}
d->status = iso_stat;
}
finish:
urb->actual_length += xfer_len;
qh->offset += xfer_len;离线
https://linux-sunxi.org/USB_OTG_Controller_Register_Guide
Supports up to 5 user configurable endpoints for bulk, isochronous, control, and interrupt bi-directional transfers
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http://davinci-linux-open-source.1494791.n2.nabble.com/DM365-uvc-gadget-td5992168.html
对USB协议没有研究， 这个问题太难了，等大神帮我填坑，或者以后再说吧
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